The week ahead in traffic, transit

Commuting temperatures will remain above 90 all week, the Capital Weather Gang says. The Code Orange air quality forecast for Tuesday means that drivers should avoid filling up their gas tanks, which releases fumes, making a bad situation worse.

The heat puts stress on any kind of machinery. It increases the risk of an engine failure, whether it's a car or a commuter train, and it stresses the human body, whether cycling or walking. Even waiting at a bus stop can be stressful in this weather.

The highway departments in the D.C. area will have their construction projects operating again by noon on Tuesday. That means that after rush hour, and while the day's heat is peaking, there will be plenty of orange barrels out to block lanes and slow down drivers.

During the recent hot weather, I've received an unusually large number of complaints from Metro riders about the heat in the rail cars. Bus riders have countered by saying that they've experienced unusually good conditions aboard the buses.

The Metro air conditioning is never going to match what you can get at home or in the office, but the equipment on individual rail cars and in underground stations does malfunction. Last summer, we had a significant problem at Metro Center when two chillers were broken down. That added to the already challenging problem of cooling a large and heavily used transfer station. Throughout the system, the equipment that sends chilled water through the underground stations is old. Metro is overhauling chillers at 17 plants that feed chilled water to the stations.

The 1000 Series cars in the middle of the trains are more than three decades old. Regular riders can usually tell right away if something is wrong with the air conditioning. Please do two things: Change cars at the next station, since the rail car next door may be much better. And report the problem car to Metro, either to the operator over the intercom, or by calling 202-637-1328 or by filling out this Metro comment form. Remember to tell them the car number.

Besides the condition of the equipment, other factors affecting the heat on a rail car include the passenger crowding, the opening and closing of the doors, the length of time the car has been in service (it takes a while to cool the cars) and whether you're sitting on the sunny side.

Nats in town
The Nationals play each night this week at 7:05 at Nationals Park. That will mean extra traffic around South Capitol and M streets, on the Southeast-Southwest Freeway and on the 11th and 14th Street bridges. It also adds passengers to the Green Line, since Navy Yard Station is the closest to the ball park.

Springfield Park & Ride
Fairfax County is building a new Park & Ride lot on Old Keane Mill Road by Springfield Boulevard. The work begins with the demolition of the former Circuit City building.

The construction site is fenced off, but it's near the area known as Bob's Slug Line, which the county says will remain open from 5:45 to 9:15 a.m. The county transportation department asks that people use the the sidewalks along Springfield Boulevard and Old Keene Mill Road to reach their carpools or buses.

Humpback Bridge
A new phase of construction has begun on the George Washington Parkway's Humpback Bridge. The old northbound lanes of the bridge will be demolished, then rebuilt. Northbound traffic is shifted temporarily to the center of the bridge.

The too-short ramp from the southbound 14th Street Bridge to the northbound parkway also will be rebuilt. During this phase of construction, the old ramp will be closed and drivers will be on a new temporary ramp.

Metro vending machines
A hundred vending machines have been upgraded to handle Metrorail passes, add value to SmarTrip cards and download SmartBenefits. Now, 446 of the system's 677 fare vending machines can accept both cash and credit or debit cards. This should decrease the lines that build up at busy stations at the start of the month and when special events occur.